Stabilizing gum forming petroleum product



I Patented is... 14, 1936 STABILIZING GUM FORMING PETRO PRODUCT Eugene 'Ayres, Swarthmor e, and Mark L. Hill,

Yefldon; Pa., assignors to Gulf Refining Company, Pittsburgh, Pa., a corporation of 'Bexas No Drawing. Application December 13, 1932.

r Serial No. 647,070

7 Claims. (oi. 44-9) This invention relates to stabilizing gum forming petroleum products; and it comprises an im proved petroleum product, such as a cracked motor fuel, lubricating oil or the like, carrying a small percentage of a; particular organic compound, which is capable of being produced by the condensation of two organic bodies of particular nature at least one of which is a derivative of naphthalene, one of said organic bodies having 10 one oxygen containing substituent,' such ies a; keto, aldehyde or hydroxyl group, the other of said bodies containingone amine nitrogen atom, and both ofsaid bodies being free from all other non-hydrocarbon substituents; nd it also com- 5 prises a process of stabilizing gum-forming mo- I tor fuels whereinsuch a fuel in a fresh or newly made condition is treated by dissolving therein a minimal amount of an organic compound having the property of increasing the induction pe- 0 riod of gum formation and also serving to reduce the rate at which gum is formed subsequent to saidinduction period, the said organic compound being one capable of production by the aforesaid condensation reactions between two organic bodies; all as more fully hereinafter set forth and as claimed. In-a prior and copending application by one of us (AyresJSerial No. 561,813, filed Sept. 8, 1931) it has been shown that certain organic substances have the power of inhibiting the formation of gum in a motor fuel during the so-called induction period of gum formation and that certain other substances have the power of retarding the rate of gum formation subsequent to that, when both inhibiting agents and retarding agents are present in'a motor fuel, there usually results a greater degree of'stability than can be obtained by the use of eitlfer oi the two agents 40- alone, or thata smaller total quantityof'the two agents in combination is required in a motor fuel to produce a given stability specification. In

the said induction period. It was also shown found to increase this induction period are called of pure oxygen under a pressure of 100 pounds, per square inch, The bomb is heated by immersing it in boiling; water. The rise oftemperature causes a rise of pressure to some maximum point dependent upon the volatility of the material be- 5 ing tested. Thebomb is kept in boiling water for 4 hours, during which time the pressure is recorded at regular intervals, say every 15 minutes. The number of minutes after the heating is startedanduntil the pressure drops, to say 5 pounds below the maximum pressure, can be used as a measure of the induction period or oxygen stability period, as it is sometimes called. Substances which, when added to the motor fuel, are

gum inhibitors or gum inhibiting agents. After 4 hours of heating, the bomb is cooled, the sample is removed and evaporated in a non-metallic dish for the determin tion of gum.

When'the induction peri d'of a motor fuel equals or exceeds the 4 hours of the test (that is, when the pressure in the bomb does not fall more than 5 pounds during the' test) an exceedingly small amount of gum is formed, whereas with 'short induction periods, the gum formed is relatively enormous in quantity. In other words, this test shows that the formation of gum is delayed or inhibited. during a certain period, beyondthis acknowledged copending application the use of, inhibiting agents and retarding agents in combination in a motor fuel is described and claimed.

, In the acknowledged application certain tests aredescribed for determining the efiicacy of any given material for use as an inhibitingor as a retarding agent. These tests may be described as follows: The well-known foxygen stability test can be usedto measure the effect of a given substance upon the induction period of a'motor fuel. According to this. test a sample of the 65 motorfuel is placed in a bomb in an atmosphere which the gum is formed at anenormously increased .rate. It-is obvious that it is highly important to prolong this initial period. With certain. changes, the oxygen stability test can also be used to measure another property of such fuels, namely the rate of gum formation after the expiration of the induction period. This rate of gum formation can be measured by a simple method which is useful in determining the eflect of added ingredients upon this property.

A sample of gasoline to be tested is advantageously obtained before it has been treated with acid. This sample is divided into several parts which parts are then treated with the same quantity of acid but of various strengths, or with dif feren'c quantities of acidof the-same strength. The object of this is to produce a series of gasolines refined to different degress, most of which will show-aninduction period of considerably less than 4 hours. Oxygen stability tests are run on these samples, the amount of .gum formed during the 4 hours of thetest being determined at the end. Since gum is formed in quantity only after the lapse of the induction period the time from the end of this period to the end of the test may be taken as the time during which gum is formed or as the time of gum formation. The total gum formed during the test is found by analysis. This quantity is then divided by the time of gum formation, which gives values for the rate of gum formation. This rate is determined for each of the various samples mentioned above. The

' sample having the least treatment with acid natmally has the shortest induction period and hence the longest time of gum formation. The rate of gum formation, however, has been found to decrease somewhat with increase in the time of gum formation. r

The results obtained as described above for the various samples of gasoline may be plotted. It is convenient'to plot the rates of gum formation as ordinates against the times of gum formation as abscissas. A smooth curve is obtained which can then be used as a standard or blank with which to compare similar curves for gasolines of different origin or treatment.

In order to testthe eifect of various addition agents on the rate of gum formation, a certain amount of one of these agents "is added to each of the gasoline samples. The samples are then again subjected to the same tests. The results obtained are compared with' the values given by the blank samples. Comparison is best made by comparing the curves obtained after the results are plotted. The agents which have been found to reduce the rate of gum formation are called gum retarding agents.

It is obvious, of course, that the above tests can be modified to a considerable extent, still giving res ts which can be used as a measure of the efiicacy of certain agents'in increasing the induction period and in reducing the rate of gum formation. In certain cases treatment with ultraviolet light or exposure to sunlight may re- ,tes'ts upon the rate of gum formation can be made upon highly refined gasolines which normally have an induction period longer than 4 hours. Another possible modification is tostop the test and to determine the amount of gum formed at a certain time interval after the end of the induction period as determined during the same test. However, the method outlined above certain common characteristics of structure and gives satisfactory results for all purposes and is sufiiciently accurate. It requires less time than most of the modifications which may be suggested. J

In the course of an extended series of experiments we have discovered certain organic compounds which act simultaneously as inhibiting and as retarding agents or as inhibitor-retarde'rs as they may be called. Upon comparing the structures and chemical constituents of these inhibitor -retarders we have been able to discern naphthylamine.

.product is .more economical.

solving them presents but little difiiculty. best concentration'of a given agent to employ the compounds as a whole being free from non-' hydrocarbon substituents. I

We have found that a product possessing the a peculiar properties of inhibitor-retarders can be prepared by the condensation of two organic. bodies, one being a cresol and the other di- -alpha For purposes of condensing the above compounds, standard methods are applicable. The following methods have generally proved satisfactory:

1. The substances are merely heated together, usually at the maximum temperature permitted by boiling points and tendencies to decompose.

2. The substances are heated together in the presence of a trace of iodine as a catalyst.

3. The substances are heated together in the presence of hydrogen chloride as a catalyst.

4. The condensation may be catalyzed by a dilute solution of sodium hydroxide.

One typical condensation reaction which may I Di-alpha naphthylamine was prepared by the I condensation of alpha naphthol with alpha naphthylamine. This product was then heated with cresol at 210 F. for several hours while maintaining an atmosphere of dry hydrogen chloride above the reaction mixture. The crude product thus obtained, when used in the proportion of 0.001'per cent by weight, was found to raise the induction period of a poorly refined cracked gasoline'from 45 to more than 240 minutes, and to reduce the gum formed during the test from 1420 to 16 mg. The condensation product of this example was folmd to reduce the rate of gum formation subsequent to the induction period to about half the value obtained when alpha naphthol was used as the inhibiting agent.

The pure condensation product of di-alpha 'naphthylamine and ortho cresol has the probable formulaamine. While we have foimd the pure product to be an advantageous inhibitor-retarder, we have found depends upon the agent itself as well as upon the'particular petroleum product to which it is The added. In some cases concentrations as low as 0.0005 per cent by weight are suflicient while in other cases the advantageous quantity to use may amount to 0.01" per cent or more. Generally the quantity added need not exceed a few thousandths of one per cent. By means or the tests set out previously it is a simple matter to ascertainthe most advantageous agent to employ and the best concentration for the purpose in question.

What we claim is:- 4 p 1. A cracked gasoline containing a small proportion 01' a crude condensation product formed by reaction of di-alpha naphthylamine with cresol. v

2. A cracked gasoline containing a small pro-- portion of a di-alpha naphthyl-methyl phenyl- V amine.

3. A cracked gasoline containing a small proportion of di-alpha naphthyl-2 methyl phenylamine. I

4. A cracked gasoline containing between .0005 and .01 per cent byweight di-alpha naphthyl-2 methyl phenylamine.

5. A cracked'gasoline containing approximately .001 per cent by weight of a crude condensation product formed by reaction between di-alpha naphthylamine and cresoL.

6. In the stabilization of gum-forming gasolines, the process which comprises adding to such a gasoline a small proportion of a stabilizing and a retarder and being represented by the following probable formula .agent having the properties of both an inhibitor 7. In the stabilization of gum forming cracked 

